The invention relates to practice bomb cartridges and more particularly to a practice bomb cartridge which will not start fires when detonated in grass or woods during the dry months.
Various types of signal cartridges are used in practice bombs which are launched from aircraft to indicate the point of bomb impact. The cartridge is fitted into the signal cavity of the practice bomb and, when the bomb is dropped, impact forces a firing pin against the signal primer, and ignites an expelling charge. The expelling charge, which is usually smokeless powder, ignites and expels a phosphorus composition, such as red phosphorus, to produce a flash of light and a puff of white smoke. While signal cartridges containing phosphorus provide, upon detonation, an excellent signal, these cartridges have the disadvantage in that the burning of the phosphorus composition start fires and therefore the cost of fire protection services and damage claims are significantly high.
In order to reduce the danger of fires, one military cartridge case is filled with an inert material, such as zinc oxide powder. Upon detonation, the expelling charge expels a cloud of zinc oxide powder. This cloud, however, is not visible at night and the use of an inert material such as zinc oxide is limited to daytime operation.
In U.S. Pat. No. 3,810,426, entitled "Gun Launched Training Projectile", which issued May 14, 1974, to Alan C. Baker, there is disclosed a marking projectile which has a flashcube mounted in the body. Upon impact of the projectile, a hammer drives actuating fingers into the base of the flashcube to fire the flashlamps and provide an impact signal.